A new methodology was developed to observe and measure tool wear during the die compaction process. The newly developed method is a non-destructive test using silicon rubber to transcript die surface profiles. Tool wear was observed and measured by recording surface roughness and diameter of the cylindrical die replicas on a surface profiler including weight loss in the die. To validate this procedure, an aluminum alloy powder without lubricant was compacted to examine the effect on die wear. The die materials were machined from several wrought and composite materials. A further dimension to the program was the variance of compaction pressures and lubricants.

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Artificial  spider  webs  are  a  challenge  for  the  special  effects  companies.   The natural  spider webs  are  displaying  incredible  mechanical  properties  combined with  a  low  density  and  a  high stickiness making them hard to reproduce. Throughout this project the aim is to produce artificial spider  webs  using  a specific  manufacturing  method,  pouring  a  mix  of  polymer  and  Naphtha  oil into  water  to  form  the  webs.   This  method  was  used  in  previous  cinematic applications  giving outstanding results for the artificial spider webs.  Unfortunately, due to the loss of it, the specific parameters,  tools and raw materials have to be found.  A material selection is given leading to a specific choice of thermoplastic polymers.  The selected material are then tested manually so they can be listed depending on the results obtained.  Finally, the most promising material seems to be TPU, thermoplastic polyurethane;  thanks to its excellent mechanical properties and good visual aspect. / Konstgjord  spindelväv  är  en  utmaning  för  specialeffektföretag.   De  naturliga spindelnäten visar  otroliga  mekaniska  egenskaper  i  kombination  med  låg densitet  och  hög  klibbighet  vilket gör  dem  svåra  att  reproducera.    Under hela  detta  projekt  är  målet  att  producera  konstgjord spindelväv med hjälp av en specifik tillverkningsmetod, hälla en blandning av polymer och naftaolja i vatten för att bilda näten.  Denna metod användes i tidigare filmiska applikationer och gav enastående resultat för de konstgjorda spindelnäten.  Tyvärr, på grund av förlusten av det, måste de specifika parametrarna, verktygen och råvarorna hittas. Ett materialval ges vilket leder till ett specifikt val av termoplastiska polymerer. Det valda materialet testas sedan manuellt så att de kan listas beroende på de erhållna resultaten.  Slutligen verkar det mest lovande materialet vara TPU, termoplastisk polyuretan; på grund av dess utmärkta mekaniska egenskaper och bra visuella aspekt.

No / Closed-form expressions for the small axial deflection and stress distribution of axially loaded rubber blocks of elliptical cross-section, whose ends are bonded to rigid plates, are derived using a superposition approach. The governing equations and conditions are satisfied exactly, based upon the classical theory of elasticity. Easily calculable expressions are derived for the corresponding apparent Young¿s modulus and the modified apparent Young¿s modulus in forms analogous to those previously given for blocks of circular cross-section.

Several rubber diaphragms, of the same type used inside an hydraulic accumulator, failed a short time after they were mounted. While there is nothing special with these failures the cost, in some cases can be high. A closer look, at the damaged diaphragms reveal an interesting nonsymmetric radial deformation accompanied in some cases by cracks. Most of the analyses regarding the failures of rubber diaphragms offer explanations only from a chemical or material science point of view. We propose in this thesis a new perspective from a mechanical-structural engineering view. Therefore the main goal of the thesis is to investigate the deformation of a diaphragm and based on this analysis to propose an explanation for formation of the cracks. It is shown that the analysis of the diaphragm problem leads to a pseudo-nonconservative system and involves a buckling, a post buckling (dynamic snap-through), an eversion, and a load response analysis. The problem is approached numerically using the nite element method. The character of pseudo-nonconservativeness of the system requires, in this case, an update of the tangent stiffness matrix with a certain stiffness correction. This new correction is proposed also. The result is valid not only for this particular problem but for the entire class of problems to which the diaphragm belongs. This correction is implemented in an existing nite element program (NIKE3D) and used to analyze the diaphragm deformation. The results indicate that under the typical load condition for a diaphragm a certain deformation pattern occurs, and this can lead to the formation of cracks. This deformation matches extremely well with the actual deformed shape of a typical failed diaphragm. It is shown that the deformation pattern depends on the structural properties of the diaphragm rather than on the magnitude of the applied load. The nonsymmetry in the diaphragm deformation and the difference in the crack development is explained also. / Ph. D.

M.S.